Update 29 Aug 2012: Please check this new blog entry when using MySQL Connector/Python v1.0 and later. The information here under is considered to be obsolete.

This post describes how to make a custom cursor returning rows as dictionaries using MySQL Connctor/Python v0.2 (or later).

Problem: you want to fetch rows from the database and return them as a dictionary with keys being the column names.

First, lets check how you would do it without any custom cursor.

cnx = mysql.connector.connect(host='localhost',database='test')
cur = cnx.cursor()
cur.execute("SELECT c1, c2 FROM t1")
result = []
columns = tuple( [d[0].decode('utf8') for d in cur.description] )
for row in cur:
  result.append(dict(zip(columns, row)))    

The above results in an output like this:

[{u'c1': datetime.datetime(2010, 10, 13, 8, 55, 35), u'c2': u'ham'},
 {u'c1': datetime.datetime(2010, 10, 13, 8, 55, 38), u'c2': u'spam'}]

Alternatively, you can code your own cursor which will return a row as a dictionary. Here is an example on how to do this:

import mysql.connector

class MySQLCursorDict(mysql.connector.cursor.MySQLCursor):
  def fetchone(self):
    row = self._fetch_row()
    if row:
      return dict(zip(self.column_names, self._row_to_python(row)))
    return None

What we did is subclassing MySQLCursor and overload the fetchone()-method. To use the above, you can do following:

cnx = mysql.connector.connect(host='localhost',database='test')
cur = cnx.cursor(cursor_class=MySQLCursorDict)
cur.execute("SELECT c1, c2 FROM t1")
rows = cur.fetchall()

The trick is to pass the cursor_class-argument when creating the cursor. (At the time of writing, I realize that the cursor_class should be part of the connection arguments to set a default for all requested cursors. We’ll change that.)

It’s a bit more elegant coding and possibilities are endless. Maybe you’d like a cursor which returns a row in XML for example.